Gearing



J. H. DORAN Oct. 11, 1938.

GEAR ING Filed July 6, 1955 Inventor John H, Doran by 1s ttor'ney.

Patented Oct. 11, 1938 UNITED STATES GEARING John H. Doran, Scotia, N.Y., assignor to General Electric Company, a corporation of New YorkApplication July 6, 1935, Serial No. 30,086

4 Claims.

The present invention relates to gearings such as are used for examplefor slowly rotating the rotor of an elastic fluid turbine after theturbine has been shut down in order to cause uniform cooling of therotor and thereby to prevent sagging thereof.

In steam turbine practice it has been found desirable to turn the rotorof the turbine after the provision of a gearing having a smaller ratio20 than the one mentioned above and consequently a heavier motor toovercome the inertia of the turbine rotor during starting.

The object of the present invention is to provide an improved gearingfor driving a turbine rotor or like rotatable element havingconsiderable inertia at different speeds by means including a single,comparatively small, high speed drive motor.

Another object of my invention is to provide an improved gearing inwhich certain gears align themselves automatically, thereby insuringuni- {0111111 pressure along the entire length of the ee For aconsideration of what I believe to be novel and my invention, attentionis directed to the following description and the claims ap pendedthereto in connection with. the accompanying drawing.

In thedrawing, Fig. 1 represents a front view. partly in section, of agearing arrangement embodying my invention; Fig. 2 is an enlarged,sectional, detailed view of Fig. 1; and Fig. 3 illustrates aperspective, exploded view of certain parts of Fig. 1.

The arrangement shown in the present instance is especially adapted forslowly rotating a turbine rotor at two different speeds of the order of2 and R. P. M. respectively. The gearing has a pinrality of parallelshafts ll, l2, l3, l4, l5 and I6 respectively. These shafts aresupported on a upper half l8. The first shaft II is driven by anelectric motor l9 connected to the shaft II by a belt drive 20. The lastshaft l6 serves to drive a turbine rotor and to this end is providedwith a gearing casing having a-lower half l1 and an gear 2! arranged tomesh during starting with .a gear 22 secured to and forming a part of aturbine rotor. Torque is transmitted from the shaft II to the shaft l2by means including a small gear 23 secured to the shaft. II and a largegear 24 associated with the shaft l 2. The shafts l2 and I3 areconnected by gears 25, 26. Similar gears 21, 28 transmit power betweenthe shafts l3 and I4, and other reducing gears 29, 30 transmit torquebetween the shafts l4 and I5. The gear 10 30 meshes with the gear 2|which latter may be moved into and out of engagement with the turbinegear 22. The direction of rotation of the different shafts and gears isindicated by arrows.

With the arrangement so far described a certain turbine rotor may bestarted and revolved at a certain speed which may be of the order of 2R. P. M. In accordance with my invention, means are provided forincreasing this speed or, from another viewpoint, for reducing the ratioof the gearing in order to revolve this'same turbine rotor at a speed offor instance 10 R. P. M. This means comprises a hydraulic couplingbetween two of the shafts for reducing or changing the speed radiobetween such shafts, and means for automatically rendering one of thegears inoperative in response to operation of the hydraulic coupling. Inthe present instance these means are associated with and connectedbetween the first shaft II and the second shaft l2. The gear 24 isconnected to the shaft l2 by a free-wheeling clutch comprising a toothedor recessed clutch member 31 disposed in a central opening 32 of thegear 24 and a plurality 'of rollers 33 interposed between the clutchmember 3| and the ad- 35 jacent wall of the gear 24 to effect torquetransmission from the gear to the shaft 12. Any well known free-wheelingclutch may be used for this purpose. During operation, rotation of thegear 24 in the direction of the arrow 34 causes the rollers 33 to bewedged between the gear 24 and the clutch member 3| and thereby toeffect rotation of the latter and consequently of the shaft [2. Thefree-wheeling clutch at the same time permits free-wheeling of theshaft, that is, rotation of the latter at a speed higher than the speedat which it can be driven from the shaft through the gears 23 and 24.Assuming that the sifaft I2 is rotated by its connection with the shaftll through gears 23 and 24, if now the speed of the V shaft I2 isincreased, then the same increase will take place with respect to theclutch member 3| whereby the connection between this clutch member andthe gear 24 through the rollers 33 is rendered inoperative. From anotherviewpoint,

-,to a high specific tooth pressure.

the rollers 33 arerelatively retarded, that is moved out of theirwedging or looking position, hence reduce this speed ratio. In thepresent instance I have shown a coupling 35 to drive the second shaft I2from the first shaft II at a speed ratio of about 1:1. The hydrauliccoupling comprises a casing having a side wall 36, a rear wall 31 and afront wall 38 united with the walls of the lower and upper casing halvesI I and I8. A partition 39 united with the rear Wall 31 and the frontwall 38 defines an upper or by-pass space and a lower or pump space. Twopositive displacement pumps, in the present instance gear pumps areprovided in the lower space, a first pump including a gear 40 secured tothe shaft II and meshing with a gear 4I secured to a shaft 42, and asecond pump including a gear 43 secured to the shaft I2 and meshing witha gear 44 secured to a shaft 45. The partition, together with theadjacent walls of the casing, defines an inlet channel 46 for the firstpump and a discharge channel 41 for the second pump. During operation,rotation of the first pump causes fluid to flow from the upper spacethrough the inlet channel 46 and the first pump. This fluid then acts asa drive fluid for the second pump, which may be termed a pump motor,causing rotation of the latter in the direction of the arrows (Fig. 2).The fluid is discharged through the channel 41 into the upper space tobe recirculated through the first pump. The partition 39 has an opening48 which may be closed by means of a hand-operated valve 49. As long asthe valve 49 is closed the fluid discharged by the first pump is forcedthrough the second pump, causing operation of the latter, that is,rotation at substantially the same speed at which the first pump isoperated. If, however, the valve 49 is open, the major portion of thefluid discharged by the first pump flows through the opening 48 into theupper space. This upper space then acts as a bypass for the first pump,rendering the latter inoperative as regards power transmission therefromto the second pump.

When a turbine rotor is to be started, the valve 49 is open. Powertransmission then from the first shaft I I to the second shaft I2 iseffected through the gears 23, 24, as described above, resulting inrotation of the turbine rotor at a speed of approximately 2 R. P. M. Inorder to increase this speed to, for instance, 10 49 is closed so as torender the hydraulic power transmission from the shaft II to the shaftI2 operative. This causes an increase in speed of the shaft I2 to aspeed substantially the same as that of the shaft II and at the sametime renders the power transmission between the mechanical gears 23, 24inoperative in the manner stated above.

The gear 2| secured to the shaft I6 normally has the lowest speed and'isaccordingly subjected It is therefore important with respect to thisgear that the torque be uniformly transmitted through the entire lengthof its teeth. To this end the gear is yieldingly supported so that itmay adjust itself during operation. In the present instance the gearshaft R. P. M., the valve,

I8 projects through eye bolts 50 having longitudinal openings 5|. Theseeye bolts extend through openings 52 in the lower half ll of the gearingcasing and are fastened to the ends of a bracket 53 having a knife edge54 resting on the casing half I1. The gear 2| may be moved into and outof engagement with the gear 22 on the turbine rotor by means including alever 55 on each side of the gear. Each lever 55 is fulcrumed on theshaft I5 and has an end portion with an opening 56 through which theshaft I6 extends. The other ends-of the levers 55 are connected by a pin51. The latter is engaged by a fork 58 secured to a lever 59 (Fig. 1).Upward movement of the free end of the lever 59 causes upward movemehtof the gear 2I whereby the latter is removed from its engagement withthe gear 22.

Having described the method of operation of my invention, together withthe apparatus which I now consider to represent the best embodimentthereof, I desire to have it understood that the apparatus shown is onlyillustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. A gearing including a first shaft, a second shaft, a gear on thefirst shaft meshing with a gear on the second shaft to change the speedof the second shaft with respect to that of the first shaft, one of thegears being directly secured to one of the shafts, means including afree-wheeling clutch for connecting the other gear to the other shaft, ahydraulic coupling connected between the shafts, and means for renderingthe hydraulic coupling operative to cause the freewheeling clutch tooverrun and to effect power transmission between the shafts through saidhydraulic coupling, the hydraulic coupling having a different torquetransmission ratio than that of the gears.

2. A gearing including a first shaft, a second shaft, a gear on thefirst shaft, another gear of 3. A gearing including a first shaft, asecond shaft, a gear on the first shaft, another gear of larger diametermeshing with the first gear, a free- Wheeling clutch between the othergear and the second shaft, and means including a hydraulic couplingfortransmitting torque from the first shaft to the second shaft at adifferent ratio than that of the gear, said coupling comprising a firstgear pump having a gear secured to the first shaft and a second gearpump having a gear secured to the second shaft and arranged to receivefluid discharged from the first gear pump.

4. A gearing including a casing, a plurality of shafts supported on thecasing, speed-reducing gear means connecting the shafts, and meansincluding a hydraulic coupling having a casing formed at least partly bythe first named casing-

